Distributor Questions-TIMING LIGHT USED!!!

[MikeIIDC@domain.elided]

Okay, I just came in from checking the timing on my '71 Scout w/304,
4-Speed, 4WD, etc.  Anyway, I got the timing set pretty well-set it at
about 5 degrees BTDC seemed optimal for idling.  I will take it out and
test drive it in a minute.
However, the point is, at first, I thought my timing light was broken.
I could not get a light off of any spark plug wire.  I [pulled out
directions and read them-moved the sensor module up to very near the
distributor cap, and then I was getting light.  Is this any indicator of
anything?
Always with my 345's I could put the spark pick-up anywhere on the wire
and get a light.  Does this mean I have a weak spark?  Bad wires?  What
else?
Also, I have a noticeably missing spark on my #8, #1, and #4 wires.
Would this be due to a weak coil?  Bad cap?  Actually, when the recent
tune up was done they gave me the wrong cap, but the other looked
practically brand new, so we re-used it.  Could this be my problem?
If it is dumping too much gasoline in or dripping oil in and fouling the
plugs, will this affect the spark from the distributor before it reaches
the plug?  Thus, should I clean the plug and see if this helps, or is
this something that only comes from one direction.  I am trying to
figure out if the electricity needs a clean outlet in order to head
through the line or not.  I am not real knowledgeable about electricity,
obviously!
So, Dan, John L, Tom(s), et.al, throw me a bone here!  What do I look
for next?

Michael